Wang Lijun, Wang Xiaoxia, Li Jianfa, Feng Xiaolan, Wang Yusen
School of Chemistry and Chemical Engineering, Shaoxing University, Shaoxing, 312000, People's Republic of China.
Nanoscale Res Lett. 2017 Sep 25;12(1):549. doi: 10.1186/s11671-017-2323-2.
In this work, hydrozincite and Zn/Al-CO hydrotalcite supported on silica aerogel were prepared via a simple and economical process and used as adsorbents for Pb(II) removal. The supported hydrozincite and Zn/Al-CO hydrotalcite possess ultra-thin thickness, high surface area, and weak crystallinity. In the batch Pb(II) adsorption experiments, the adsorbents with higher Zn(II) contents showed higher Pb(II) adsorption capacities, and the adsorption data fitted well with the Langmuir isotherm model and pseudo-second-order kinetic model, indicating a mechanism of surface chemisorption. The adsorption capacities calculated based Langmuir isotherm model are 684.9 mg/g and 555.6 mg/g for the supported hydrozincite and Zn/Al-CO hydrotalcite, respectively, higher than the adsorption capacities of other hydrotalcite-based adsorbents and most of other inorganic adsorbents reported previously. The XRD diffraction peaks of hydrozincite and Zn/Al-CO hydrotalcite disappeared after the adsorption, and the Pb(II) species were uniformly dispersed in the adsorbents in form of Pb(CO)(OH) proven by TEM, EDS mapping and XRD analysis, demonstrating the nature of the adsorption is the precipitation conversion of hydrozincite or Zn/Al-CO hydrotalcite into Pb(CO)(OH). These results demonstrate the synergic Pb(II) removal effect of the CO and OH derived from hydrozincite and Zn/Al-CO hydrotalcite together with their ultra-thin thickness and high surface area contribute the excellent properties of the adsorbents.
在本工作中，通过简单且经济的工艺制备了负载于二氧化硅气凝胶上的碱式碳酸锌和Zn/Al-CO水滑石，并将其用作去除Pb(II)的吸附剂。负载型碱式碳酸锌和Zn/Al-CO水滑石具有超薄的厚度、高比表面积和弱结晶度。在批量Pb(II)吸附实验中，具有较高Zn(II)含量的吸附剂表现出更高的Pb(II)吸附容量，吸附数据与Langmuir等温线模型和准二级动力学模型拟合良好，表明其吸附机制为表面化学吸附。基于Langmuir等温线模型计算得到的负载型碱式碳酸锌和Zn/Al-CO水滑石的吸附容量分别为684.9 mg/g和555.6 mg/g，高于其他基于水滑石的吸附剂以及先前报道的大多数其他无机吸附剂的吸附容量。吸附后碱式碳酸锌和Zn/Al-CO水滑石的XRD衍射峰消失，通过TEM、EDS映射和XRD分析证明，Pb(II)物种以Pb(CO)(OH)的形式均匀分散在吸附剂中，表明吸附的本质是碱式碳酸锌或Zn/Al-CO水滑石沉淀转化为Pb(CO)(OH)。这些结果表明，碱式碳酸锌和Zn/Al-CO水滑石衍生的CO和OH对Pb(II)具有协同去除作用，同时它们的超薄厚度和高比表面积赋予了吸附剂优异的性能。
